Circuit card connecting devices, such as card racks and other host devices of pluggable modules, often have guides for guiding the insertion of a circuit card into a card receptacle on a back panel. Attempts have been made to develop removable card guides so that circuit cards having different sizes may be inserted on the same back panel. For example, U.S. Pat. No. 4,068,290 to Wetherbee, issued on Jan. 10, 1978, discloses a circuit card guide adapted to be fastened to a card rack in a temporary fashion between permanently attached card guides so as to permit the guiding and retaining of circuit cards having a width substantially less than the spacing between the permanent guides. However, to install or remove the circuit card guide disclosed in Wetherbee, access to the back of the card rack is required. This is a disadvantage because accessing the back of the rack may cause interruption of the operation of cards in the rack. It may also be inconvenient to access the back of the rack, for example, when the rack is large and its back is close to a wall.
In a simple construction, a card guide can have a screw end so that it can be screwed into the front side of the back panel. However, such a guide is difficult to use because it is difficult to orient the guide. Further, when the guide is long it may be unstable.
U.S. Pat. No. 6,552,915 to Takahashi et al, issued on Apr. 22, 2003, discloses a telecommunications apparatus with a sub-rack unit into which an intermediate guide rail member may be inserted from the front. The intermediate guide rail member is mounted by tightening a lock bolt member similarly inserted from the front of the sub-rack unit. The intermediate guide rail member allows the sub-rack to accommodate smaller cards. While the intermediate guide rail member is mountable from the front side of the apparatus, it still has some disadvantages. The construction of the sub-rack unit and of the intermediate guide rail member is complicated. The sub-rack unit occupies a large surface area on the apparatus and may not be suitable for use in applications where space is limited such as when multiple circuit cards need to be closely housed. The sub-rack unit and the intermediate guide rail members are also not suitable for mounting on many existing racks or connecting devices, such as many standard circuit card connecting devices. Further, such a sub-rack unit limits the permissible maximum length of a sub-card and is not suitable for use in devices such as Small Form Pluggable (SFP) and 10 Gigabit Small Form Factor Pluggable (XFP) devices where it is desirable to maximize the accessible length of a card plugged therein.
Therefore, there is a need for a removable and front installable circuit card guide that has a simple construction and can be installed on different back panels, particularly on existing standard back panels.